A successive approximation analog-digital converter (ADC) generates different reference voltages with an internal digital-analog converter (DAC) and compares the voltage of an analog signal to be converted with the reference voltages in order to generate a digital signal corresponding to the voltage of the analog signal to be converted. An example of a successive approximation ADC has a resolution corresponding to the number of passive components in the internal DAC, i.e. a resolution of N bits for 2N passive components (where N is a natural number).
In order to increase the resolution of such successive approximation ADC, a greater number of passive components needs to be provided in the internal DAC. Increasing the number of passive components in the DAC, however, raises manufacturing costs. Furthermore, conversion speed decreases and power consumption increases due to the increased time constant during analog-digital conversion.